Possesion
by Tharesa
Summary: Reaction story to 10x3 where Cas and Sam caught Dean as a demon to cure him. Destiel.


" _It's over! Dean, it's over."_

Castiel had jumped the demon from behind and had a vice-like grip around his torso, forcing his arms to his sides. The demon snarled at him furiously, but Castiel refused to let go. The new grace inside of him was simply too powerful for the monster to do more than writhe in his arms.

Castiel transported himself and the Winchesters to the dungeon, where he shoved the demon into chair and bound him tightly using a combination of warded and normal chains and cuffs. The demon screamed at him in frustration, but Castiel kept a straight face as he gestured for Sam to continue the treatment.

He watched in silence as Sam injected another dose of human blood into the demon's veins. The demon screamed again, but his face almost instantly contorted into a mask of sheer agony.

"Son of a bitch!" He hissed through clenched teeth. Sam placed the empty vial on the table and turned to Castiel, ignoring his brother's cursing.

"You okay if I take a break?"

"Of course. Feel better." Castiel replied with only half of the awkwardness he'd had in the past.

Sam huffed a tired laugh. "Thanks, Cas." He said before closing the doors to the dungeon.

Castiel fiddled with the materials on the table, trying his best to ignore the pained breath that filled the silent room. A few minutes after Sam had gone, the breath stopped altogether, tempting the angel to look up. He fought the urge until an all-too familiar voice spoke his name.

The angel looked up on impulse, finding an unexpected pair of green eyes watching him. The demon smiled. "Long time no see. How ya been, Cas?"

Castiel did not respond. He did not move. He did nothing.

The demon smirked. "You're lookin' good. I'm diggin' those wings."

Castiel narrowed his eyes and tilted his head, confusion evident. "You can see my true form?" He asked, hostilities momentarily forgotten.

"Ah! That gotcha talkin'. Everythin's a bit fuzzy 'cuz of the damn human blood, but yeah, I can see it. Doesn't look right on ya. I take it you didn't get your own grace back from Metadouche?"

Castiel shut down again. He should not be talking with this demonic version of Dean, even if it _was_ Dean, in some twisted way. He simply could not be trusted.

"Aww, Cas! Don't be so tough on me, man. It's me, Dean. You can tell me anything, you know that."

"I do not trust your judgment as a demon." Castiel deadpanned.

Dean snorted. "I sure as Hell don't trust your judgment _ever,_ but that hasn't stopped me from talkin' to ya."

Castiel relented, but he kept his reply short. This was not the Dean he knew; this was a contorted, twisted creature filled with hatred and violence, as evident by the black soul braided with hellfire that had replaced the vibrant blue light Castiel had loved to see so dearly within Dean's torso.

"No. I did not retrieve my grace."

"Damn. Well, at least I know what _not_ to fantasize about." The demon grumbled.

Castiel choked on air, coughing and sputtering, which elicited laughter from Dean. "Gotcha, angel."

At that moment, Castiel wished he could leave. Go get Sam and never come back until _his Dean_ was back. This was no conversation he wanted to have with demon Dean. This was not the soul he had fallen for on so many different occasions.

"Are ya just gonna keep starin' at me? Gettin' an eyeful before I turn into a lame-ass human again?" Dean asked, clearly trying to agitate Castiel further. But the angel noticed that his last question was more of a statement. The demon was watching him for a reaction, green eyes now black.

"What are you trying to imply?" Castiel snapped. His tolerance for these comments was running short.

"Imply? Cas, babe, I wasn't bein' metaphorical." Dean winked suggestively, but Castiel glared at him.

"This is not a conversation I want to have with _you_." He replied frostily. He tore his gaze from the demon and refocused on fiddling with the materials on the table.

"Aww, why not? _I've_ never had the balls to say it before."

Castiel refused to reply. The silence stretched until Dean must have reached a point where he found it intolerable, choosing to push the subject.

"Mmm, Cas, if I had you locked up right now...ooo, the things I would do to you." Dean drew out the syllables of nearly every word, making the statement as sensual as possible. It managed to send a chill down the angel's spine. The words hung in the air, only adding to the tension Castiel felt by simply being in the room.

"There is nothing wrong with being human." Castiel stated, changing the subject. He had been reminded of the demon's earlier statement; _"...lame-ass human"_.

Dean chuckled darkly, not thrown by the change in the slightest. "There are so many things wrong with being human. Emotions, for one. I mean, look at you! You were an emotionless bastard when I first met you, and now you're riddled with so many emotions that you can't even remember what it's like without 'em! Not to mention all the shit and power you've lost because of 'em."

As the demon got further into his speech, the words became more and more heated, until he snarled out the last few. The words rang around the chamber for a moment, before Castiel angrily placed whatever tool was in his hand on the table and turned to Dean.

"If it wasn't for the _weakness_ you seem to think I have acquired, you likely wouldn't be alive!" He growled. Dean returned his glare with just as much fire.

"Are you expecting a thank you? 'Cuz you sure as Hell ain't gettin' one. You're the one who decided to break angel-law by hangin' around with me and Sammy when you easily could'a kept your ass in Heaven. _You're the fucking idiot who fell in love with someone so full of self-hatred that he couldn't get passed his problems until he became one if the monsters you hate most!_ "

Castiel stared agape at Dean, but the demon wasn't finished. A malicious cackle trickled out of his lips, sending a new round of chills down Castiel's spine–but these were much less welcome.

"You think you hid it so well, huh? You think that after five years of putting on a straight face, we wouldn't be able to tell. Well, lemme tell ya a little story, Cas."

"I do not wish to have this conversation with you!" The angel snapped, repeating his earlier statement. He felt both flustered and furious, and he did not want to listen to this twisted of the man he loved _mock_ the feelings he had for him.

"Stories aren't conversations, Cas, they're narratives." Dean shot back. Castiel panicked behind the glare he used to mask his fear. What could the demon possibly want to tell him?

"Do you remember when that dick Zachariah popped me to the future? Year 2014, ironically enough. It was a post-apocalyptic wasteland. And I mean Biblical. I had said 'no' to Michael, Sam had said 'yes' to Lucifer, life on Earth was literally Hell, and the angels had flown the coop.

"I saw Baby. My future self had let her rot away, and I remember feeling so, so sad for that broken car.

"I remember myself. I was a douchebag, as per usual, and I couldn't care less who lived or died.

"And I remember you. Castiel, angel of the Lord, dumped on his ass by his fellow angels and left to die with the humans, _as a human_. Nobody wanted you. Not your own kind, not the poor bastards you and I were stuck with, not even future me."

Dean finally paused, the smirk that tainted his lips having dissipated slightly. Castiel watched, entranced yet horrified by the story, as Dean's face fell into a look of confusion mixed with sadness. The demon was no longer looking at him; his gaze rested on the floor.

"You were so _wasted._ You drank so much, smoked and swallowed so many drugs. If it weren't for the tiny piece of grace you had, you probably would've died within the first few months. But you hadn't.

"I remember going on a mission to fight Lucifer. I rode with you in your jeep, and so I asked you, 'Cas, everyone here treats you like shit. Even me–future me–treats you like shit. Why do you stay?'"

Dean stopped, looking up at Castiel expectantly.

"What?" Castiel asked, taking the bait.

"Aren'cha gonna ask me what you said?"

"Those were not _my_ words." Castiel snapped. Dean cocked an eyebrow as if daring Castiel to _just ask_.

"Fine. What did I say?"

"You turned to me, grinned like the dumb-ass you were, and said, 'I stay for you. Dean Winchester, the man I fell in love with. Every now and then you show up in my Dean, and that is why I stay.'"

Silence. Castiel left Dean in silence. He couldn't take it anymore. This wasn't Dean, it wasn't _Dean_ , _it is not Dean!_

He had his hand poised to fling open the door so he could escape, but the next words that caught his ears froze him in place.

"I can still feel it. I can feel one thing, Cas. One goddamn emotion outta all the other ones I had bottled up. Besides hatred and violence, though those don't really feel like they used to..." Dean mused, trailing off for a moment before regaining focus.

"What I was feeling when end-of-the-world you said that to me. L–."

"Don't." Castiel's voice cracked, but he couldn't let this demon finish that sentence, "Don't say it. Please don't. I don't want to hear it from you. I won't!" Castiel yelled, unnecessarily banging his fist against the door.

"Why're you afraid? Tell me why you're afraid to hear those words when you've wanted to hear them since the day you met me. _Tell me!_ " Dean screamed the last phrase, making Castiel flinch. He whirled around, prepared to reply with heated words, but faltered when he saw the raw expression on Dean's face. It was as if he'd been truly offended that Castiel had stopped him. It didn't make any sense to the angel.

"You're lying." He answered finally, breath shaky.

"No, Cas. I'm really not." Dean smirked again, but Castiel knew him well enough to see that it was a halfhearted gesture. "Tell me why I would lie about it."

"You want to hurt me. You're a demon, I'm an angel. It's only natural."

Dean chuckled that dark laugh again. He closed his eyes and hummed. "Yeah, Cas, I wanna hurt you _so bad_. I wanna sink my teeth into your skin until you _bleed_. I wanna hold you so _tight_ between my fingers that your skin bruises. I want to make you _scream._ " The demon made obscene gestures with his hands and face that only emphasized what he was imagining aloud to the angel. "It'd be so different, getting' to see your angelface instead'a Jimmy's. And you'd get to see my gorgeous demonface up-close and personal. It's only natural, Cas, couldn'ta said it better myself. The angel and the demon. Lovers damned by fate. It'd be like Romeo and Juliet with less suicide."

"I do not understand that reference." Castiel huffed on impulse. Somehow his comment managed to throw Dean entirely off course.

"Wait, seriously? Out of all the junk Sammy and I made you watch, you _never_ saw Romeo and Juliet?"

"No."

"Dude. Shakespeare is classic. That can't even be possible." Dean scoffed.

"A lot of things should not be possible." Castiel replied shortly, uninterested in explaining why he had never bothered to join his siblings in seeing a Shakespeare performance during that time in history. The angel leaned ungraciously against the door and crossed his arms over his chest.

"Maybe we should dub ourselves 'Team Possible'. It fits." Dean commented.

Castiel fought the sudden urge to smile–he had recognized Dean's _Kim Possible_ reference. He settled for just nodding.

"So. What'dya say?"

"About what?" Castiel asked, unprepared for the subject change. He was unsure whether Dean was referring to _Kim Possible_ or something else entirely.

"Me an' you. And put the damn prejudice aside for a second. Angel, demon, human, none'a that matters."

"I don't understand what you're asking." Castiel snapped, although he was catching on. Half of him wished Dean would drop the subject while the other half _desperately_ wished he would continue it _._

"Have sex with me."

"Th-that's not a question!" Castiel sputtered, staring at Dean for being so blunt. Not even in his drunkest moments could Castiel remember Dean being so outright and uninhibited in any of his desires.

"No, it's not." Dean chuckled, a hungry look appearing on his face.

"Dean..." Castiel began aimlessly, trailing off and just staring at the demon.

"Please." Dean nearly whispered; the pure want in his voice caught Castiel's attention. He swallowed nervously.

Castiel shook his head. "No."

The angel didn't know why he was refusing. He had–far too easily–put prejudice aside. Yes, Dean was a demon...but he was still _Dean._ And he would be human again as soon as Sam finished the treatments. Castiel wanted to. He wanted Dean. There was nothing stopping him. Nothing except...

"You would not be emotionally invested. For you, it would just be a physical act."

"Didn't I just tell you that I–?" Dean snapped, but Castiel hastily cut him off.

"And we established that you were lying. Besides, you might regret it once you're human again."

It was Dean's turn to stare in shock, but his shock quickly turned to anger.

"You say that as if being a demon is the same as being wasted! You say that as if I think you're some one-night stand. That's not what this is." Dean glared at Castiel for a solid minute before adding, "You know what your problem is, Cas? You think you're worthless. Which is bullshit. You matter, but you don't believe it. All I wanna do is prove it to you."

"I don't want you to prove anything." Castiel snapped, offended by Dean's blatant yet accurate assessment.

"Liar."

Castiel took a deep, steadying breath before giving in. "I meant that you don't have to prove anything to me because I trust you, Dean."

The demon was silent for a moment, his expression giving away his internal song of _Hallelujah._ Then he quirked his fingers in a gesture for Castiel to come to him as his expression melted into lust. The angel took tentative steps forward, until he was standing directly in front of Dean. Hesitantly, Castiel placed on hand on Dean's shoulder while the other braced his weight by grasping one of his arms. Dean's hand latched onto the sleeve of Castiel's trench coat, and his gaze flitted between Castiel's eyes and lips, all traces of demonic ego suddenly wiped from his features.

Castiel leaned in closer so that mere centimeters separated them. He paused, unsure how to proceed–and admittedly dazzled by green eyes–before Dean took the initiative and closed the distance. Castiel felt his breath hitch as his heart skipped a beat and then accelerated at the touch of Dean's lips against his own.

Dean's eyelids had slid closed at the contact, leaving Castiel to follow his lead by closing his own. Castiel felt teeth nip his bottom lip, again and again, harder and more forcefully each time, until Castiel gasped from the pain of the most recent one and pulled away. The angel opened his eyes and shifted his weight, bringing the hand from the chair to his lips. He pressed a finger against them and drew it away to find a spot of blood on his skin. He shot a glare at Dean that vanished when he saw the demon watching him with jet black eyes, Castiel's blood dotting his lips.

"What, can't handle a little blood?" He teased, grinning arrogantly at Castiel. Just to rub it in, the demon licked his lips. Slowly.

"Bite me." Castiel snapped automatically, which made the demon laugh.

"Already did."

Castiel rolled his eyes slightly, and this time a semi-genuine smile graced the demon's face.

"Always thought that was cute." He said, and for the first time Castiel noticed that Dean's voice was gruffer than usual.

"Interesting."

"Hmm?"

Castiel hadn't realized that he'd thought aloud, but before he could consider backtracking, Dean tugged on his sleeve. Castiel shrugged and explained, "Your voice is different."

Dean smiled that almost-there smile again. "Kiss me, angel."

Castiel relented with much less resistance this time, placing his hand back on the chair and leaning into Dean's fervent kisses. Out of nowhere, Castiel was consumed by his own wave of passion, and in it he found himself climbing onto the chair so that he was semi-straddling Dean's waist with one foot balancing him on the floor. The demon chuckled against his lips, which only enticed Castiel to get as close as physically possible to him. The chair teetered slightly when the angel moved, but he used the stolen grace to balance it against gravity.

Dean began nipping at his lips again, but this time Castiel copied him until Dean opted to use his tongue instead. He pushed at the gap between Castiel's lips until the angel let go and allowed Dean's hot, slimy muscle to slide into his mouth.

The groan Castiel emitted at that touch was unabashedly shameful. He could compare the feeling to other experiences of his life if he so chose, but to compare Dean Winchester to anything else would be akin to blasphemy.

Castiel was reminded who he was with, and as Dean pulled the angel's tongue into his own mouth, the passion Castiel had been so laden with subsided into tender warmth, a feeling he knew well. This was the man he loved, the man he raised from perdition, the man whose broken soul he had pieced back to perfection.

This was no demon.

This was Dean.

Castiel pulled away, retracting his tongue and letting Dean do the same before tucking his head in the crook of Dean's neck and leaning his cheek against the demon's.

"Cas?" Dean whispered, clearly unsure why the angel had stopped.

"Say it." Castiel whispered back.

"Say what?"

"How you felt."

Dean huffed a laugh. "Castiel, always so needy. I want you to _work_ for it."

"What do you want me to do?"

" _Have sex with me_ , Cas."

"Not here."

"Then you won't get it here."

"I find that acceptable."

They were silent until Dean turned his face away from Castiel's.

"You should get Sam." He grumbled. Castiel stood back and nodded, keeping his eyes trained away from Dean. He trudged back to the door and laid his fingers on the handle.

"Dean?" The angel asked shyly, his back still turned to the demon.

"Yeah." Dean grunted, acknowledging that he was listening.

"Raincheck?"

Dean's cheery laugh filled the silence, and Castiel smiled to himself.

"Wouldn't have it any other way."

With that, Castiel opened the door and left in search of Sam.


End file.
